Could you pass the STAAR physics test?

The following questions released from the Texas Education Agency were adapted from a STAAR physics end-of-course exam.

Questions:

1. A car is traveling at 21.0 m/s. It slows to a stop at a constant rate over 5.00 s. How far does the car travel during those 5.00 seconds before it stops?

2. A 5.000 kg crate is accelerated from 5.000 m/s to 10.00 m/s. What is the amount of work needed to accelerate the crate, to the nearest tenth of a joule?

3. Using a diffraction grating, a student looks at an incandescent lightbulb and a hydrogen-gas-discharge tube. Why does the student see fewer colors from the hydrogen-gas-discharge tube than from the incandescent lightbulb?